The pharmacokinetics of ibuprofen (Motrin) are best described by a two-compartment open model. Ibuprofen pharmacokinetics are only minimally influenced by advanced age, the presence of alcoholic liver disease, or rheumatoid arthritis. Levels of ibuprofen in breast milk are negligible. In addition, ibuprofen can be combined with acetaminophen without altering the pharmacokinetic profile. However, although not yet clinically proved, the concomitant use of ibuprofen and aspirin appears to reduce ibuprofen plasma levels to less than half those observed with ibuprofen alone.